Therapeutic effects of photodynamic therapy (PDT) are limited by cancer hypoxia because the PDT process is dependent on O2 concentration. Herein, we design biocompatible manganese ferrite nanoparticle-anchored mesoporous silica nanoparticles (MFMSNs) to overcome hypoxia, consequently enhancing the therapeutic efficiency of PDT. By exploiting the continuous O2-evolving property of MnFe2O4 nanoparticles through the Fenton reaction, MFMSNs relieve hypoxic condition using a small amount of nanoparticles and improve therapeutic outcomes of PDT for tumors in vivo. In addition, MFMSNs exhibit T2 contrast effect in magnetic resonance imaging (MRI), allowing in vivo tracking of MFMSNs. These findings demonstrate great potential of MFMSNs for theranostic agents in cancer therapy.
Plasma- and chemical-grafted amidoxime/carbon nanofiber hybrids (p-AO/CNFs and c-AO/CNFs) were utilized to remove 238U(VI) and 241Am(III) from aqueous solutions, seawater, and groundwater. Characteristic results indicated more nitrogen-containing groups in p-AO/CNFs compared to c-AO/CNFs. The maximum adsorption capacities of p-AO/CNFs at pH 3.5 and T = 293 K (588.24 mg of 238U(VI)/g and 40.79 mg of 241Am(III)/g from aqueous solutions, respectively) were significantly higher than those of c-AO/CNFs (263.18 and 22.77 mg/g for 238U(VI) and 241Am(III), respectively), which indicated that plasma-grafting was a highly effective, low-cost, and environmentally friendly method. Adsorption of 238U(VI) on AO/CNFs from aqueous solutions was significantly higher than that of 238U(VI) from seawater and groundwater; moreover, AO/CNFs displayed the highest effective selectivity for 238U(VI) compared to the other radionuclides. Adsorption of 238U(VI) onto AO/CNFs created inner-sphere complexes (e.g., U–C shells) as shown by X-ray absorption fine structure analysis, which was supported by surface complexation modeling. Three inner-sphere complexes gave excellent fits to pH-edge and isothermal adsorption of 238U(VI) on the AO/CNFs. These observations are crucial for the utilization of plasma-grafted, AO-based composites in the preconcentration and immobilization of lanthanides and actinides in environmental remediation.
Phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3 or PIP3 ) mediates signalling pathways as a second messenger in response to extracellular signals. Although primordial functions of phospholipids and RNAs have been hypothesized in the 'RNA world', physiological RNA-phospholipid interactions and their involvement in essential cellular processes have remained a mystery. We explicate the contribution of lipid-binding long non-coding RNAs (lncRNAs) in cancer cells. Among them, long intergenic non-coding RNA for kinase activation (LINK-A) directly interacts with the AKT pleckstrin homology domain and PIP 3 at the single-nucleotide level, facilitating AKT-PIP3 interaction and consequent enzymatic activation. LINK-A-dependent AKT hyperactivation leads to tumorigenesis and resistance to AKT inhibitors. Genomic deletions of the LINK-A PIP3 -binding motif dramatically sensitized breast cancer cells to AKT inhibitors. Furthermore, meta-analysis showed the correlation between LINK-A expression and incidence of a single nucleotide polymorphism (rs12095274: A > G), AKT phosphorylation status, and poor outcomes for breast and lung cancer patients. PIP 3 -binding lncRNA modulates AKT activation with broad clinical implications.
When using liquid chromatography/mass spectrometry (LC/MS) to perform untargeted metabolomics, it is now routine to detect tens of thousands of features from biological samples. Poor understanding of the data, however, has complicated interpretation and masked the number of unique metabolites actually being measured in an experiment. Here we place an upper bound on the number of unique metabolites detected in Escherichia coli samples analyzed with one untargeted metabolomics method. We first group multiple features arising from the same analyte, which we call “degenerate features”, using a context-driven annotation approach. Surprisingly, this analysis revealed thousands of previously unreported degeneracies that reduced the number of unique analytes to ∼2961. We then applied an orthogonal approach to remove nonbiological features from the data using the 13C-based credentialing technology. This further reduced the number of unique analytes to less than 1000. Our 90% reduction in data is 5-fold greater than previously published studies. On the basis of the results, we propose an alternative approach to untargeted metabolomics that relies on thoroughly annotated reference data sets. To this end, we introduce the creDBle database (http://creDBle.wustl.edu), which contains accurate mass, retention time, and MS/MS fragmentation data as well as annotations of all credentialed features.
Efficient photoelectrochemical water oxidation may open a way to produce energy from renewable solar power. In biology, generation of fuel due to water oxidation happens efficiently on an immense scale during the light reactions of photosynthesis. To oxidize water, photosynthetic organisms have evolved a highly conserved protein complex, Photosystem II. Within that complex, water oxidation happens at the CaMn4O5 inorganic catalytic cluster, the so-called oxygen-evolving complex (OEC), which cycles through storage “S” states as it accumulates oxidizing equivalents and produces molecular oxygen. In recent years, there has been significant progress in understanding the OEC as it evolves through the catalytic cycle. Studies have combined conventional and femtosecond X-ray crystallography with extended X-ray absorption fine structure (EXAFS) and quantum mechanics/molecular mechanics (QM/MM) methods and have addressed changes in protonation states of μ-oxo bridges and the coordination of substrate water through the analysis of ammonia binding as a chemical analog of water. These advances are thought to be critical to understanding the catalytic cycle since protonation states regulate the relative stability of different redox states and the geometry of the OEC. Therefore, establishing the mechanism for substrate water binding and the nature of protonation/redox state transitions in the OEC is essential for understanding the catalytic cycle of O2 evolution. The structure of the dark-stable S1 state has been a target for X-ray crystallography for the past 15 years. However, traditional X-ray crystallography has been hampered by radiation-induced reduction of the OEC. Very recently, a revolutionary X-ray free electron laser (XFEL) technique was applied to PSII to reveal atomic positions at 1.95 Å without radiation damage, which brought us closer than ever to establishing the ultimate structure of the OEC in the S1 state. However, the atom positions in this crystal structure are still not consistent with high-resolution EXAFS spectroscopy, partially due to the poorly resolved oxygen positions next to Mn centers and partial reduction due to extended dark adaptation of the sample. These inconsistencies led to the new models of the OEC with an alternative low oxidation state and raised questions on the protonation state of the cluster, especially the O5 μ-oxo bridge. This Account summarizes the most recent models of the OEC that emerged from QM/MM, EXAFS and femtosecond X-ray crystallography methods. When PSII in the S1 state is exposed to light, the S1 state is advanced to the higher oxidation states and eventually binds substrate water molecules. Identifying the substrate waters is of paramount importance for establishing the water-oxidation mechanism but is complicated by a large number of spectroscopically similar waters. Water analogues can, therefore, be helpful because they serve as spectroscopic markers that help to track the motion of the substrate waters. Due to a close structural and electronic similarity to water, ammonia has been of particular interest. We review three competing hypotheses on substrate water/ammonia binding and compile theoretical and experimental evidence to support them. Binding of ammonia as a sixth ligand to Mn4 during the S1 → S2 transition seems to satisfy most of the criteria, especially the most compelling recent EPR data on D1-D61A mutated PSII. Such a binding mode suggests delivery of water from the “narrow” channel through a “carousel” rearrangement of waters around Mn4 upon the S2 → S3 transition. An alternative hypothesis suggests water delivery through the “large” channel on the Ca side. However, both water delivery paths lead to a similar S3 structure, seemingly reaching consensus on the nature of the last detectable S-state intermediate in the Kok cycle before O2 evolution.
The balance between detrimental, pro-aging, often stochastic processes and counteracting homeostatic mechanisms largely determines the progression of aging. There is substantial evidence suggesting that the endocannabinoid system (ECS) is part of the latter system because it modulates the physiological processes underlying aging. The activity of the ECS declines during aging, as CB1 receptor expression and coupling to G proteins are reduced in the brain tissues of older animals and the levels of the major endocannabinoid 2-arachidonoylglycerol (2-AG) are lower. However, a direct link between endocannabinoid tone and aging symptoms has not been demonstrated. Here we show that a low dose of Δ9-tetrahydrocannabinol (THC) reversed the age-related decline in cognitive performance of mice aged 12 and 18 months. This behavioral effect was accompanied by enhanced expression of synaptic marker proteins and increased hippocampal spine density. THC treatment restored hippocampal gene transcription patterns such that the expression profiles of THC-treated mice aged 12 months closely resembled those of THC-free animals aged 2 months. The transcriptional effects of THC were critically dependent on glutamatergic CB1 receptors and histone acetylation, as their inhibition blocked the beneficial effects of THC. Thus, restoration of CB1 signaling in old individuals could be an effective strategy to treat age-related cognitive impairments.
Clustered regularly interspaced short palindromic repeats (CRISPR)-Cpf1 has emerged as an effective genome editing tool in animals. Here we compare the activity of Cpf1 from Acidaminococcus sp. BV3L6 (As) and Lachnospiraceae bacterium ND2006 (Lb) in plants, using a dual RNA polymerase II promoter expression system. LbCpf1 generated biallelic mutations at nearly 100% efficiency at four independent sites in rice T0 transgenic plants. Moreover, we repurposed AsCpf1 and LbCpf1 for efficient transcriptional repression in Arabidopsis, and demonstrated a more than tenfold reduction in miR159b transcription. Our data suggest promising applications of CRISPR-Cpf1 for editing plant genomes and modulating the plant transcriptome.
Decoding the principles of cluster-based framework assembly at the molecular level remains a persistent challenge. Herein, we isolated and characterized a novel water-stable three-dimensional (3D) metal–organic open framework [Cl@Ag14(cPrCC)10Cl2·(p-TOS)·1/3H2O] n (SD/Ag14, cPrCCH = cyclopropylacetylene; p-TOS = p-toluenesulfonate), which contains a chloride-templated Ag14 cluster as building block. For SD/Ag14, one chloride acts as the template to shape the Ag14 cluster and the other bridges the clusters to a 3D pcu-h open framework. As revealed by high resolution electrospray mass spectrometry (HRESI-MS), the Ag12–Ag14 species are potential cluster-based intermediates to the 3D pcu-h framework, which authenticates a preconceived idea that the 3D framework is hierarchically assembled from the silver clusters as observed in solid state. Interestingly, SD/Ag14 can be used effectively to remove the environmental pollutant Cr2O7 2– from wastewater through anion exchange in a single-crystal-to-single-crystal (SC–SC) transformation fashion. Furthermore, SD/Ag14 exhibits excellent antibacterial activity against Staphylococcus aureus, thus making it a potential antibacterial agent.